The present invention relates to a technology of a right-angle coaxial connector in which a pin-type terminal on a coaxial plug provided at an end of a cable is oriented in a direction different by 90 degrees from an axial direction of the cable.
The right-angle coaxial connector includes a coaxial plug and a coaxial receptacle. The coaxial plug is used, for example, such that the coaxial plug is provided at an end of a coaxial cable. The coaxial receptacle is used, for example, such that the coaxial receptacle is mounted to a board or the like.
In association with recent tendency toward small-size and light-weight electronic equipments, rapid progress has been made in miniaturizing coaxial connectors per se. Japanese Utility Model Application Laid-open No. Hei 5-33481 discloses particularly a technology of a right-angle coaxial connector, in which the thickness of a coaxial plug can be reduced particularly. Japanese Patent Application Laid-open No. Hei 5-266951 discloses a technology that can suppress the height of a fitting portion of a coaxial connector with a simple construction.
The right-angle coaxial connectors of this type are, in general, designed such that a ground terminal of a coaxial plug is constructed by a metal shell as disclosed by these publications. For example, a fitting portion of the coaxial plug to the coaxial receptacle is provided with a signal terminal connected to a central conductor of a cable, and a ground terminal made up of a metal shell connected to an outer conductor of the cable. The ground terminal is formed into a cylindrical shape surrounding the signal terminal, and formed of electrically conductive metal throughout.
On the other hand, the coaxial receptacle is provided with a recessed portion (a hole) into which the signal terminal of the coaxial plug and the cylindrical grand terminal thereof are insertable entirely. Within the recessed portion, signal contacts are provided to be electrically connected with the signal terminal and the ground terminals through contact.
The coaxial plug in the prior art may encounter the following problems in relation to the construction in which the metal shell serving also as the ground terminal is in the form of the cylindrical shape surrounding the signal terminal and formed of the electrically conductive metal throughout.
For example, when the coaxial receptacle is mounted to a board, or the coaxial plug is connected to the coaxial receptacle, electrically conductive metal wastes and so on may find their way into the connected portion (fitting portion) therebetween for some reason. In the case where the metal wastes are in the connected portion, there is a possibility that a short circuit occurs between the signal terminal and the metal shell. This problem becomes more serious as the connector is reduced in size, and a countermeasure against this problem is required. In particular, in a case of a super-miniature connector whose coaxial plug is several millimeters in diameter, there is a high possibility that a short circuit occurs between the signal terminal and the metal shell due to the metal dust, particles or the like, and thus the countermeasure for preventing this is important.
In the coaxial plug of the prior art, a metal plate is processed into a cylindrical shape to form the ground terminal serving also as the metal shell, and therefore there arises another problem in that the mass production applicability is low and the cost is high.
Accordingly, an object of the present invention is to provide a right-angle coaxial connector which can eliminate a possibility of electrical short circuits, and which is excellent in mass production applicability, and which can be manufactured with low cost.
A coaxial connector for right-angled connection according to the present invention comprises a coaxial plug provided at an end of a cable, and a coaxial receptacle electrically connected to the coaxial plug by inserting the coaxial plug therein, characterized in that: the coaxial plug includes a plug main body made of an insulative resin, and a plurality of pin type terminals protruded from a surface of the plug main body; and the pin type terminals are divided into one signal terminal and a plurality of ground terminals disposed around the signal terminal.
According to the present invention, the coaxial plug has one signal terminal and the plurality of ground terminals disposed around the signal terminal, and these terminals are each in the form of the pin type, and protrudes from the surface of the insulative plug main body. In particular, the ground terminal is not the cylindrical, but rather is a pin type in contrast to the prior art, and therefore clearances are formed between the terminals. Consequently, even if metal waste, particles, and the like find their way into the clearances between the terminals, they can easily pass through the clearances and they can be removed easily therefrom. Accordingly, the possibility of electric short circuits can be eliminated. Further, the entire housing is formed of resin, and a ground terminal serving also as a metal shell, which is low in productivity, is not used. Accordingly, the mass production applicability is improved, and manufacture with low cost can be realized.
It is preferable that the ground terminals of the invention are arranged such that distances between adjacent ground terminals are also equal to each other. By setting the clearances between adjacent terminals equal, the electric field distribution around the signal terminal can be made uniform, and the shielding effect by the ground terminals can be enhanced.
It is preferable that the ground terminals are arranged such that distances from the signal terminal to the ground terminals are also equal to one another. By setting the distances from the signal terminal to the ground terminals to be equal to one another, the electric field distribution around the signal terminal can be made more uniform, and the shielding effect by the ground terminals can be enhanced.
In another embodiment of the invention, a surface of the plug main body is partially formed into a planar surface extending in an axial direction of the cable and the signal terminal is disposed at a central portion of the planar surface protrudes from the planar surface, while the ground terminals are disposed around the signal terminal. By arranging the terminals on the planar surface extending in the axial direction of the cable to be protruded from the planar surface, the form of the right-angle coaxial plug can be maintained, while a simple arrangement that makes it difficult for the metal wastes to enter into or to stay in the clearances between the terminals can be realized.
As least two or more ground terminals are preferably used. However, from the viewpoint of controlling the electric field distribution by the ground terminals, in a case where the two ground terminals are provided, it is preferable that the two ground terminals are disposed to be point-symmetric with respect to the signal terminal. In a case where three ground terminals are provided, it is preferable that the ground terminals are disposed at respective apex positions of a regular imaginary triangle with the signal terminal inside of the triangle.
Where four ground terminals are provided, it is preferable that the ground terminals are disposed at respective corner portions of an imaginary square centered around the signal terminal. Where eight ground terminals are provided, it is preferable that the ground terminals are respectively disposed at corner portions of an imaginary square centered about the signal terminal and at middle points of the sides of the imaginary square.
In another embodiment, the coaxial receptacle includes an insulative housing having a surface formed with a plurality of guide holes into which the signal and ground terminals are respectively inserted, and a plurality of contacts disposed within the guide holes of the insulative housing. The receptacle contacts include a signal contact contacted with the plug, signal terminal and a plurality of ground contacts contacted with the plug ground terminals. The surface of the insulative housing has a planar portion surface-contacted with the planar surface of the coaxial plug.
By providing the coaxial receptacle with the plurality of guide holes independently and respectively corresponding to the signal and ground terminals, even if minute metal wastes and so on find their way into the guide holes, a short circuit between the signal terminal and the ground terminal will not occur. Since the surface of the insulative housing has a planar portion, it can be contacted with the planar surface of the coaxial plug, thereby preventing the formation of a clearance between the receptacle and the plug.
In another embodiment, can also be used in which the insulative housing of the coaxial receptacle has a side surface intersecting the surface thereof, and a stopper portion is provided in a boundary portion to the planar surface of the plug main body so as to be contacted with the side surface of the insulative housing, thereby restricting a displacement of the plug main body in a direction about an axis of the signal terminal when the coaxial plug is connected to the coaxial receptacle. This construction makes it possible to reliably position the coaxial plug with respect to the coaxial receptacle, and maintain the excellent connected state therebetween.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.